"Roar" of blaNDM-1 and "silence" of blaOXA-58 co-exist in Acinetobacter pittii.

Acinetobacter pittii 44551 was recovered from a patient with gout combined with tuberculosis and was found to harbor the carbapenemase genes blaNDM-1 and blaOXA-58 on two different plasmids pNDM-44551 and pOXA58-44551, respectively. pNDM-44551 displayed high self-transferability across multiple bacterial species, while pOXA58-44551 was likely co-transferable with pNDM-44551 into A. baumannii receipts. pNDM-44551 was a close variant of the previously characterized pNDM-BJ01, and the blaNDM-1 gene cluster was arranged sequentially as orfA, ISAba14, aphA6, ISAba125, blaNDM-1, bleMBL, ΔtrpF, dsbC, tnpR, and zeta. pOXA58-44551 was a repAci9-containing plasmid, and blaOXA-58 was embedded in a 372F-ISAba3-like-blaOXA-58-ISAba3 structure. The mobile genetic platforms of blaNDM-1 and blaOXA-58 herein showed some differences from their previously characterized variants. The production of NDM-1 in strain 44551 contributed the majority to its high resistance to carbapenems, while the blaOXA-58 stayed silent most likely due to the lack of an upstream promoter to drive its transcription. Increased surveillance of Acinetobacter co-harboring blaNDM-1 (active) and blaOXA-58 (either active or silent) is urgently needed.